What are lysosomes and what is their function?

Lysosomes are specialised vesicles within cells that contain digestive enzymes to break down waste materials and cellular debris.

Lysosomes, often referred to as the 'suicide bags' of the cell, are small, round organelles covered with a single layer of membrane. They are found in nearly every animal-like eukaryotic cell. Their primary function is to serve as the cell's waste disposal system. They accomplish this by digesting unwanted materials in the cytoplasm, both from outside of the cell and from within.

Lysosomes contain a variety of enzymes, known as hydrolases, that are capable of breaking down all types of biological polymers—proteins, nucleic acids, carbohydrates, and lipids. These enzymes are active at a much lower pH (more acidic) than the cytoplasm, thus the enzymes will not be active until they are inside the lysosome, protecting the cytoplasm from being digested.

The process of digestion in the lysosome involves the fusion of the lysosome with another organelle or vesicle, forming a single, larger vesicle. The lysosomal enzymes then break down the material in the vesicle. The digested components are then either recycled within the cell or excreted.

Lysosomes also play a key role in cell death, a process known as autolysis. When a cell is damaged or dying, the lysosomes break open, releasing their digestive enzymes into the cytoplasm of the cell, leading to complete breakdown and death of the cell. This is why lysosomes are sometimes referred to as 'suicide bags'.

In addition to their role in waste disposal and cell death, lysosomes are also involved in other cellular processes, such as secretion, plasma membrane repair, cell signalling, and energy metabolism. Therefore, lysosomes are essential for maintaining the health and functionality of a cell.

In summary, lysosomes are vital organelles in the cell that perform a variety of functions, all of which contribute to the cell's overall health and survival. They are the cell's primary defence against waste and cellular debris, and they also play a role in cell death and other cellular processes.